Self-advancing mine roof supports and control means therefor



May 16, 1967 A D, ALLEN ET AL 3,320,001

SELFADVANCING MINE ROOF SUPPORTS AND CONTROL MEANS THEREFOR 4 Sheets-Sheet l Filed Jan.. 18, 1965 `1 mvENToRs :n u BY g i l 2', ond- Atty.

lrcHARo WA R May 16, 1967 A. D. ALLEN ET ALK 3,320,001

` SELF-ADVANCING MINE ROOF SUPFORTS AND CONTRDL MEANS THEREFOR Filed Jan. 18, 1965 4 Sheets-Sheet 2 INVENTORI ARcHELAius o. ALLI-:N

Mmmm WARD Mwv' MW R6, H967 A. D. ALLEN ET AL SELFADVANCING MINE ROOF SUPPORTS AND CONTROLl MEANS THEREFOR 4 Sheets-Sheet Filed Jan. lf3, 1.965

INVENTORI n. ALLEN Mamma WA R p BY May 16, 1967 A. D. ALLEN ETAL SELF-ADVANCING MINE ROOF SUPPORTS AND CONTROL MEANS THEREFOR Filed Jan. 18, 1965 Anaal-:mias Rica-*AR m WAR o D. ALLEN 4 Sheets-Sheet 4 INVENTORS face, each support having United States Patent lOiiice 3,320,001 Patented May 16, 1967 3,320,001 SELF-ADVANCING MINE ROOF SUPPORTS AND CNTROL MEANS THEREFOR Archelains D. Alien, Leyland, and Richard Ward, Worsley, England, assigner-s to Gullick Limited, Wigan, England, a British company Filed Ian'. 18, 1965, Ser. No. 426,070 Claims priority, application Great Britain, Fei). 7, 1964, 5,273/ 64 Claims. (Cl. 299-1) This invention is for improvements in or relating to mine roof supports and the operation thereof.

The invention is concerned more particularly with mine roof support systems of the kind comprising a series of self-advancing hydraulically extensible chocks or supports, the advance of each chock in the series being initiated by the advancing ofl a predecessor in the series. A ram means is incorporated in each support or chock and serves to push over the conveyor as cutting of the coal from the coal face proceeds. After the conveyor has been pushed over the chocks are advanced up to it. Actual advancing of the chocks may be effected by the retraction of the rams which serve to push over the conveyor, said rams being anchored to the conveyor. Alternatively, the supports or chocks may be in two parts (ie. they may be walking checks), one part serving as an anchorage or abutment for the ad vance of the other part by hydraulic ram means incorporated in the support.

In practice the supports are advanced in turn towards the coal face behind the coal cutter as it cuts or ploughs the coal from the face and into the conveyor.

lIt is important that the supports in such a system should not in any circumstances advance towards the coal face until they have been passed by the cutter. An object of the invention is to ensure this.

According to the present invention there is provided a self-advancing mine roof support for supporting a mine roof in the vicinity of the path of movement of a mineral (eg. coal) cutting machine along the mineral face, said support having means for advancing it and a control means for said advancing means, said control means including a device, responsive to the passage of a wal cutting machine, arranged so that the advancing means will not operate to advance the support until the cutting machine has passed the support and acted directly or indirectly on said device.

According to a further feature of the invention there is provided a series of self-advancing mine roof supports in side-by-side relationship for supporting a mine roof in the vicinity of the mineral (e.g. coal) cutting path of movement of a machine along the mineral a pressure-fluid ram means for advancing it after the cutting machine has passed,

`a solenoid. or electromagnetically-operated control valve for each ram means, a sequence relay, in the solenoid or coil circuit of each of `said valves, adapted to be actuated by re-positioning of a preceding support in the series, a memory relay in the solenoid or coil circuit of each of said valves, and a photo-electric cell energising circuit, for each memory relay, including a photo-cell associated with each support and arranged to be energise-d by a light source on the mineral cutting machine as it passes, whereby a support cannot be advanced until a preceding support has been re-positioned and the cutting machine has passed the support.

Two particular embodiments of the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings in' which:

FIGURE 1 is a diagram showing a fragment of a 'photo-electric sensing arrangement,

ber of the supports as FIGURE 2 shows one of FIGURE 3 is a rdiagram showing a fragment of a hydraulic sensing arrangement,

FIGURE 4 is a diagram showing an over-current protection circuit for the system shown in FIGURE 1,

FIGURE 5 is a diagram showing a circuit designed to prevent laccidental operation of the system shown in FIGURE 1 by an unintended light source, e.g. a miners lamp, and

FIGURES 6 and 7 are semi-diagrammatic views showing a suitable form of lamp arrangement for use with the system shown in FIGURE 1.

The arrangement shown in FIGURE 1 is designed to fulfill the following requirements:

(a) To initiate the Ihydraulic action to advance and set each chock behind the coal cutter as it progresses along the coal face,

(b) To4 make sure that the cutter has passed each chock before that chock can advance,

(c) To ensure that no chock can advance out of turn ahead of the cutter,

(d) To provide a warning if any chock fails to advance or if the advancing chocks fall too far behind the cutter.

Brieily, the electrical equipment on each chock cornprises a high current (eg. cadmium sulphide) photoelectric cell 10, a memory relay having a relay coil 11a and contacts 11b, a `sequence relay in the form of a pressure switch 12 and a solenoid-operated hydraulic valve 13. A hold-on relay 10a is connected in parallel with the photo-electric cell. A diode may be connected across the relay coil 11a for intrinsic safety.

The electricity supply lines are designated E in FIG- URE 1 and the hydraulic mains are designated H.

Referring now to FIGURE 3, the prop or chock which is shown by way of example, comprises a base 14 to which is hingedly attached, at 15, a robust member 16 carrying at its upper part a roof-engaging plate 17. The member 16 is applied to the roof by means of a hydraulic leg or jack` 18 pivotally mounted on the base 14, as indicated at 19, and also pivotally attached to the -mernber 1'6 at 20. There may be more than one of the hydraulic legs or jacks 18 associated with the member 16.

The pressure switch 12 is operated at a predetermined hydraulic pressure (the setting pressure) in the leg 13 for a purpose to be hereinafter described.

Housed in the base 14 is a double-acting hydraulic ram 21, the cylinder of which is pivotally attached to the base at 22. The piston rod 23 of the ram is adapted at its outermost end for attachment to a clevis or bracket 24 on the conveyor 25.

It will be appreciated that there will be a large numjust described arranged side-by-side the supports or chocks,

along the coal face.

In the position shown in FIGURE 2 the piston rod 23 of the ra-.rn 21 has just `been extended so as to push the conveyor 25 up to the newly exposed coal face. The next step will Ibe to remove the top coal Lto half the seam height, rby means of a Ranging Shearer type cutting machine, which provides access over the un-cut coal for the plate 17 during the next step which will be t-o retract the ram so that, using the conveyor as an anchorage, the roof support will be drawn up to the conveyor.

The coal cutter 26 is equipped with a light 27 on a trailing boom 28. This light source illuminates the photocell 10 on each chock in turn as it passes. On being illuminated the photo-electric-cell energises the memory relay 11a, 11b which holds itself ON through the pair of auxiliary contacts 10a thus remembering that the cutter has passed.V

The hydraulic system whereby the advance of each chock in the series is initiated by a predecessor in the series includes piston valves 13a and 13b under the control of striker valves 13e` adapted to -be operated by the rams 21. The arrangement is such that when a ram 21 has fully advanced its support it sets the piston Ivalves of the next support in a position ready for the advance of that support.

The fvalve 13 which starts the advancing and setting cycle, of its particular chock, is arranged to be energised Athrough the closing of the normally open contacts of the pressure switch 12 on the preceding chock and by the closing, as just described, of the normally open contacts of the relay 11b on its own chock. The relay contacts 11a are connected in series with the contacts of the pressure switch 12.

The arrangement just described operates as follows:

Assuming that a chock is in the process `of setting, (i.e. the conveyor has been advanced, the chock has been drawn up to it and the hydraulic leg 18 is being extended) when it has reached full setting pressure the pressure switch 12, on that chock, is operated to connect the solenoid valve 13 on the following chock to the hydraulic power supply and clear its own memory by opening its normally closed contacts. The following chock will now start its advance and setting cycle if its memory has been energised, through the photo-electric arrangement 10, 27, by the passing of the cutter. If its memory has not been energised then it will wait for the cutter to pass and then start its cycle. Thus, in normal operation, chocks are advanced and set one at a time, close behind the cutter and only one chock can be energised and advanced at a time.

The possibility of the following fault conditions arising is anticipated and catered for in the design of the control circuit and in the operating procedure:

(a) Failure of power supplies either electrical or hydraulic.

(b) Failure of any chock to reach full setting pressure due to any mal-function in the chock.

(c) Accidental operation of a memory circuit ahead of the cutter, by, for example, a miners helmet lamp.

(d) Selection of more than one chock at a time by energising more than one solenoid valve.

(e) Lagging of chock advance too far behind the cutter.

(f) Sticking of pressure switches either in the ON or OFF position.

The following safety devices are fitted'to the system:

(1) Over-current devices on `both memory and solenoid valve supply lines.

(2) VVoltage failure relays on feed and return lines of the relay supply.

(3) A rectifier and warning lamp, indicated at 29 and 30 respectively, connected in series across the solenoid and its associated relay contact on each chock.

(4) A switch on the control panel which reverses the 4polarity of the solenoid valve supply with a circuit which indicates if any current is taken in the reversed condition.

As regards the fault conditions (a) to (f) referred to above, the manner in which the safety devices and certain operating procedures take care -of and detect them is as follows:

Failure of either hydraulic supply or the electrical supply to the solenoid valves will stop the sequence of chocks advancing and setting, but will not affect the memory circuits. Failure of the supply t-o the memory circuits will stop the chocks advancing and will also stop the memory circuits from operating.

If the sequence of chocks advancing is interrupted, but the memory circuits still function, ya condition occurs as the cutter proceeds in which several memories are energised at one time. The over-current device at the control panel is set so that if more than a predetermined number of memories or solenoids are energised yat once, it gives an alarm signal.

An over-current detector circuit for the purpose just described is shown in FIGURE 4 of the drawings. This over-current detector circuit is connected on the supply lines and takes the form of a direct current amplifier coupled to a trip relay. The circuit comprises a long tail pair transistor amplifier 3K2, `the trip relay 33, a setting potentiometer 3-4 and a series resistance 35. S indicates the supply input and S1 the D.C. output to the coal face lines.

The potentiometer 34 is set so that in normal conditions transistor TR1 conducts and in this condition the current through the coil of the trip relay 33 in the collector circuit of TR2 is negligible. When the ycurrent through the series resistor 35 exceeds a certain value, determined by the setting of the potentiometer 34, transistor TR2 conducts and energises the trip relay 33. The relay 33 then, through its contacts, operates whatever tripping and warning devices are required to deal with this abnormal condition.

The potentiometer 34 may be calibrated in terms of the number of memories or, when used in the solenoid lines, the number of the solenoids which must be operated lline also takes care of (b) and (e) as either of these conditions will cause the operation of several memories, in the case of (b) by stopping the sequence altogether and in the case of (e) by lagging so far behind the cutter that several memories are energised.

Fault condition (c) is prevented by an operating procedure. Immediately prior to the cutter starting its run, the memory line is switched off and then on again. Switching off clears all memories and as no man will be on the face ahead of the cutter, during its run, accidental operation of a memory cannot recur. A further safeguard is in the memory line overcurrent device (FIGURE 4) as, if this is set correctly, it will detect that a memory has been energised in addition to those in normal operation.

To make the system substantially immune from accidental operation, e.g. due to illumination of the photoelectric cells by the lamp o-n a miners helmet, the arrangement shown in FIGURE 5 may be adopted. This arrangement utilises an A C. coupled photo-cell circuit which will only respond to a modulated light source such as a lamp connected to A.C. mains. In 'the arrangement shown in FIGURE 6 a photo-transistor 37 is used as a light detector and is connected in a circuit which will give maximum alternating current output due to excitation with modulated light. The photo-transistor is capacitor coupled to an output transistor 38 which operates 'the memory relay 11a, 11b. 'The output "transistor '38 receives no signal when the photo-transistor 37 is illuminated with unmodulated light (e.g. the light from a miners lamp) but will have a direct current signal applied to its base, via the rectifier 39 connected from base to emitter, when modulated light of a predetermined frequency acts on the photo-transistor.

The light source 27 on the boom 28 attached to the cutting machine may be a fluorescent lamp 40 (see FIGURES 6 and 7) which gives a well modulated output on alternating current. Such a lamp can be yarranged to give a narrow band or column of light at right-angles to the length of the face so that a large vertical error in the relative position of the cutting machine and chock can be tolerated, the light spread to each side of the illuminated chock being cut down to a low level. The arrangement just referred to may be achieved, for example, by using a long semi-cylindrical lens 41 (see FIGURES 6 and 7) in front of the lamp 40 and a troughshaped reliector 42 behind it.

As an alternative to the just-described arrangement for avoiding accidental operation of the system by, for example, a miners lamp such as a helmet lamp, a photocell may be used which is only sensitive to violet and ultra-violet light. For instance, the light 27 could be a fluorescent lamp having a high violet and ultra-violet output. If necessary, a filter or filters could be located between the light source and the photo-electric cells so as to filter out all light except the violet and ultra-violet. In this connection it should be borne in mind that the normal lamp used by a miner produces a light which is very weak at the blue end of the spectrum and would not, therefore, operate a photo-cell designed to be energised by violet or ultra-violet light.

Fault condition (d), selection of more than one solenoid at a time, is prevented by an over-current device similar to that on the memory relay line (FIGURE 6), but set to operate the alarm if two or more valves are energised.

Fault lcondition (f) is detected for switches sticking in the OFF position by the memory line over-current device (FIGURE 4) as this condition in any chock will interrupt the setting cycle, but not the memory circuits. For sticking in the ON position another operating procedure is used. Before the start of the run, the polarity of the solenoid valve supply line is temporarily reversed. The rectifier and warning lamp 29, 30 above referred to are connected in series across the solenoid and its relay contacts are so polarised, that in normal operation, they pass no current. However, on reverse polarity the rectifier will pass a current lighting the lamp if the pressure switch is operated to complete the circuit to the common line, i.e., if it is stuck ON, as at the start of a cycle, the pressure switches should all be OFF A current detecting device on the control panel gives warning if any switch is stuck and the warning light shows on which chock the offending switch is located. This is in fact the one before that shown by the warning light, yas the solenoid is -operated from the switch on the previous chock.

Each chock is also provided with a control valve 36 to provide for manual operation when required.

The system shown in FIGURE 3 is similar in some respects to the system shown in FIGURE l and where applicable like referen-ce numerals have been used to designate like parts. In each chock there is embodied a trip valve, with a memory arrangement, operated by the coal cutting machine. The actual trip valve, which is engaged by a part of the cutting machine as it passes, is

indicated at 311. With this arrangement, although a preceding chock may have instructed the next chock to advance, the latter will be unable to obey unless it has been passed by the cutter.

We claim:

1. A series of self-advancing mine roof supports in side-byside relationship for supporting a mine roof in the vicinity of the path of movement of a mineral cutting machine along the -mineral face, each of said supports having in combination a pressure-fluid ram means for advancing it after the cutting machine has passed, a solenoid-operated control valve for said ram means, a sequence relay in the solenoid circuit of said valve, means for actuating said sequence relay by re-positioning of a preceding support in the series, a memory relay in the solenoid circuit of said valve, and a photo-electric energising circuit for said memory relay including a photo-cell positioned to be energised by a light source on a mineral cutting machine as it passes the support, whereby a support cannot be advanced until a preceding support has been re-positioned and the cutting machine has passed.

2. A series of supports as claimed in claim 1 wherein an over-current sensitive protection device is provided in the -circuit of the memory relays.

3. A series of supports as claimed in claim 1 wherein an over-current sensitive device is provided in the circuit of the sequence relays.

4. A series of supports as claimed in claim 1 wherein the memory circuits are in a loop circuit and wherein voltage failure relays are tted to the feed and return lines of said loop circuit to detect any break in the loop and operate an alarm signal.

5. A series of roof supports as claimed in claim 1 wherein a rectifier and warning lamp are connected in series across the solenoid of each ram control valve, the arrangement being such that no current passes through the rectifier and warning lamp except when the sequence relay sticks in the ON condition.

References Cited by the Examiner UNITED STATES PATENTS 2,760,134 8/1956` Johnson 318-480 X 3,243,964 4/1966 Thomas et al 6l-45.2

FOREIGN PATENTS 1,347,827 l 1/1963 France.

823,128 11/ 1959 Great Britain.

ERNEST R. PURSER, Primary Examiner. 

1. A SERIES OF SELF-ADVANCING MINE ROOF SUPPORTS IN SIDE-BY-SIDE RELATIONSHIP FOR SUPPORTING A MINE ROOF IN THE VICINITY OF THE PATH OF MOVEMENT OF A MINERAL CUTTING MACHINE ALONG THE MINERAL FACE, EACH OF SAID SUPPORTS HAVING IN COMBINATION A PRESSURE-FLUID RAM MEANS FOR ADVANCING IT AFTER THE CUTTING MACHINE HAS PASSED, A SOLENOID-OPERATED CONTROL VALVE FOR SAID RAM MEANS, A SEQUENCE RELAY IN THE SOLENOID CIRCUIT OF SAID VALVE, MEANS FOR ACTUATING SAID SEQUENCE RELAY BY RE-POSITIONING OF A PRECEDING SUPPORT IN THE SERIES, A MEMORY RELAY IN THE SOLENOID CIRCUIT OF SAID VALVE, AND A PHOTO-ELECTRIC ENERGISING CIRCUIT FOR SAID MEMORY RELAY INCLUDING A PHOTO-CELL POSITIONED TO BE ENERGISED BY A LIGHT SOURCE ON A MINERAL CUTTING MACHINE AS IT PASSES THE SUPPORT, WHEREBY A SUPPORT CANNOT BE ADVANCED UNTIL A PRECEDING SUPPORT HAS BEEN RE-POSITIONED AND THE CUTTING MACHINE HAS PASSED. 